Non-linear tunnel hull boat

Abstract

This tunnel-hull uses non-linear flow means to maximize tunnel lift efficiency, fuel economy, and directional stability. The lower lateral hull planing surfaces have sharp, wedge-shaped step discontinuities defining multiple flat, smooth, planing surface sections having zero dead-rise angle. The steps decrease wetted surface area and increase hydrodynamic traction without adding draft. Downwardly extending curved lateral hull portions define a tunnel between their parallel inner edges. Random impressions in the undersurface of the tunnel relieve vacuum suction and create non-linear air flow for greater lift. Downwardly bent front edges of the tunnel and rear delta wing swim platforms are control surfaces that serve as safety brakes and prevent flipping. Tunnel air pressure increases in a gradient from bow to stern placing the center of lift aft of the center of mass, which provides safety from undue inclination and extra shock absorption. The planing surfaces are, alternatively in the form of endless rolling belts, which allow beaching and amphibious operation with high efficiency and without damage to the hull.

What is claimed is: 
     
       1. A non-linear tunnel hull, consisting of: a pair of transversely curved and spaced, longitudinally extending parallel hull sections, and a longitudinally extending connecting section therebetween cooperating with said hull sections to define a tunnel extending from the fore end to the aft end of said hull, said tunnel being open at both ends and having surface impressions into the undersurface not less than 0.5 centimeters in depth and not more than 10 centimeters in depth, said hull sections having downwardly facing planing surfaces with parallel inner edges in common with lateral hull sections and with said tunnel, the distance between said inner edges defining the tunnel width which is the same at the fore end as it is at the aft end, said planing surfaces having no fewer than one wedge-shaped step break per 5 meters of length of said planing surface and no more than 3 wedge-shaped step breaks per meter of length of said planing surface, said step breaks having a height of not less than 0.2 percent of the length of said planing surfaces and not more than 0.8 percent of the length of said planing surfaces, said height being measured at said inner edges where it has a maximum value, said height decreasing to zero at the outer edges of said planing surfaces to define the wedge-shaped step breaks, said step breaks defining multiple planing surface sections each having zero dead-rise angle and no curvature about the transverse axis, said tunnel having a flat triangular roof with the apex at the fore end of said hull, said tunnel roof being parallel to the static water line, the plane of said roof having a constant angle of inclination of at least 5° relative to said planing surfaces. 
     
     
       2. The hull according to claim 1, wherein the vertical portion of said step breaks are perpendicular to said planing surfaces. 
     
     
       3. The hull according to claim 2, wherein said surface impressions are randomly sized and randomly placed into the undersurface of said tunnel, said planing surfaces have a width of at most one third of said tunnel width, said planing surfaces have one said step break per meter of length of said planing surfaces, and the perpendicular distance between the plane of said planing surfaces and said tunnel roof measured at the transom is at least 20 percent of said tunnel width. 
     
     
       4. The hull according to claim 2, wherein the fore end portion of said tunnel is bent downward relative to the plane of said roof of said tunnel at an angle of not less than 5° and not more than 80° and is a control surface. 
     
     
       5. The hull according to claim 4, wherein said lateral hull sections rise in cylindrical curvature from said planing surfaces at an angle of at least 135° measured at the transom, the measure of said angle gradually decreasing toward the fore end of said planing surfaces. 
     
     
       6. The hull according to claim 5, wherein the aft quarter of the outer sides of said lateral hull sections curve outwardly to form delta wing swim platforms having longitudinal inclination angle relative to the plane of said planing surfaces of at least the measure of the angle of said roof of said tunnel relative to said planing surfaces. 
     
     
       7. The hull according to claim 6, wherein said fore end portion of said tunnel and said delta wing swim platforms are mechanically rotatable, adjustable control surfaces. 
     
     
       8. The hull according to claim 1, wherein said planing surfaces are in the form of endless rolling belts attached to said lateral hull sections by rollers.